docs: def content(self, content):
          """
          Overwrite Dockerfile with specified content
          :param content: string to be written to Dockerfile
          """
          if self.cache_content:
              self.cached_content = b2u(content)
  
          try:
              with self._open_dockerfile('wb') as dockerfile:
                  dockerfile.write(u2b(content))
          except (IOError, OSError) as ex:
              logger.error("Couldn't write content to dockerfile: %r", ex)
              raise